Member Avatar for vince_2x

Hi guys!

sorry if this question has been asked b4.

I just wanna know what is the difference between a==b and a is b?

Thanks

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  • Latest Post Latest Post by bumsfeld
Member Avatar for bumsfeld

If you have two lists like
list1 = [1, 2, 3]
list2 = [1, 2, 3]
then
list1 == list2 is True, they have equal content
but
list1 is list2 would give False, they are not the same object.

Member Avatar for vince_2x

Hi guys!

sorry if this question has been asked b4.

I just wanna know what is the difference between a==b and a is b?

Thanks

Thank you very much for this exellent reply

I have also notice that if you do id(list1) and id(list2) they are both stored in different memory location.

Now, a point to note is that when you do something like

>>> a = "string"
>>> b = "string"
>>> id(a)
11147264
>>> id(b)
11147264

AND observe this one

>>> a = "string"
>>> b = "string "
>>> id(a)
11147264
>>> id(b)
12922656
>>>

I dont understand.. does in the first situation, is b pointing to a, unlike in the second case where b has a white space at the end..

Any idea, how python manage this???

Thanks

Member Avatar for bumsfeld

>>> a = "string"
>>> b = "string"
>>> id(a)
11147264
>>> id(b)
11147264

"string" is really the object here, an immutable object, so both a and b reference the same object. Now, if you use "string ", then string with a space is a different and new object.

In the case with the two lists, you have a mutable object that can be changed in place, like you could reverse list1 but not list2. For that reason list1 and list2 have different references.

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